Two-Variable Categorical Data

DAP: Day 2

If you want to inspire confidence, giveplenty of statistics. It does not matter

that they should be accurate, or even intelligible, as long as there is enough of them.

-Lewis Carroll

Monday, May 24, 2010

Categorical Data

Two-Way TablesA two-way or contingency table is when two or more categorical variables are compared. The following table contains data on students’ politics.

PoliticsPoliticsPoliticsPoliticsPoliticsPolitics

Gender

L M C Total

Gender Female 35 36 6 77Gender

Male 50 44 21 115

TotalTotal 85 80 27 192

The data in the table are the counts for each category.The total number of students involved is 192.

MARGINAL DISTRIBUTIONS

Monday, May 24, 2010

Categorical Data

Two-Way TablesAnswer the following questions using the data in the table.

PoliticsPoliticsPoliticsPoliticsPoliticsPolitics

Gender

L M C Total

Gender Female 35 36 6 77Gender

Male 50 44 21 115

TotalTotal 85 80 27 192

1. What percent of the class is male?2. What of the class considers themselves to be “Conservative”?3. What percent of the males in the class consider themselves to be “Conservative”?4. What percent of all students in the class are males who consider themselves to be “Conservative”?

Monday, May 24, 2010

Lets Make a Picture•Comparing different variables.

•Here we can compare the percentages of the political preferences to gender. Does gender have an influence over political preference?

•For Liberal, it seems that they are about equally divided, however for conservative 22% are Female and 78% are Male.

Categorical Data

0%

25%

50%

75%

100%

Female Male

Liberal Moderate Conserative

Monday, May 24, 2010

Smoking and Education•In your groups complete the Smoking and Education worksheet.•Use the post-it notes to write up a solution to show to the class.

Categorical Data

Really bad idea.

Monday, May 24, 2010